Place in saucepan over med heat; let it melt. Cook until a ring of little bubbles appears around the edge of melted sugar/butter mixture.,Whisk in 1/2 cup heavy cream. Cook until bubbles reappear. Remove from heat.,Add 1 tsp vanilla.,______,Place 3/4 cup frosting on top of bottom layer. Add 2nd layer and frost with remaining icing. Do this quickly so it doesn't set up before you finish spreading.